I would suggest you to watch"Batman:The Animated Series" because its one of the best cartoon shows that was ever created,the plot is really well written,mature and pretty dark at times and the characters are great.This is also the series in which Harley Quinn was introduced for the first time ever.
I know a short way to get you into Catwoman, Harley Quinn, and Poison Ivy and that's through an AWESOME web series that takes place in the same universe called Gotham Girls, which has those three and Batgirl. It has three seasons, each season has ten episodes, and the episodes are never any longer than four or five minutes, so it wouldn't take you long to get through it. I'll post it on your club so you can get the enjoyment! You should definitely watch Batman: The Animated Series, but I think you'll enjoy this web series A LOT because it focuses A LOT on Catwoman, Harley, and Ivy.